A storage area network (SAN) is made up of two primary components: storage systems and a logically isolated network. The storage systems may include disks, tapes, and SAN-management software, that must be SAN-capable. The network may include adapters, wiring, bridges, hubs, switches, and directors. Adapters attach servers and peripherals to the wiring in the network. Bridges are used to convert from one protocol to another. Hubs, switches, and directors provide a central connection point and routing capability. Currently, a large number of SANs utilize fibre channel to provide connections for processors and storage systems on the SAN.
FICON (fiber connection) is a high-speed input/output (I/O) interface for mainframe computer connections to storage devices based on the NCITS fibre channel standard (FC-SB-2), and SANs are available in the market that are based on FICON. FICON products use a mapping layer that is based on the ANSI (American National Standards Institute) X3.230-1994 fibre channel—physical and signaling interface standard (FC-PH) that specifies physical signaling, cabling and transmission speeds for fibre channel. Because FICON is based on the industry-standard fibre channel architecture, the fiber infrastructure and fiber directors of a network can be shared between different types of servers. For example, fiber interfaces can readily be switched between FICON and FCP (Fibre Channel Protocol).
Interface errors (IFCCs) in a FICON enabled SAN may be caused by a resource provides mechanisms needed to transfer data blocks of data end-to-end. FC4 is the highest level layer in the fibre channel standards set. FC4 defines the mapping between the lower level layers of the fibre channel and Upper Layer Protocols such as the IPI and SCSI command sets, the HIPPI data framing, and other ULPs. As a result of the timeouts discussed above, exchanges will be aborted, and errors will be logged.
A fibre channel has potentially hundreds of open exchanges. As a result, use of the above-described method of taking a resource offline provides a potential for causing hundreds of abnormally terminated exchanges. This is problematic because it may result in a perception of poor quality of the SAN, undue service calls, and can drive a large warranty cost to investigate the cause of such errors.
To avoid the problems discussed above, there is a need to eliminate or reduce the detrimental effects of the taking resources offline.